Method and apparatus for radio link management in sidelink communication

Abstract

An operation method of a first terminal, in a communication system supporting sidelink communication, may include transmitting one or more sidelink data to a second terminal; performing a monitoring operation to receive one or more hybrid automatic repeat request (HARQ) responses for the one or more sidelink data from the second terminal; and declaring a radio link failure (RLF) for a radio link between the first terminal and the second terminal when the one or more HARQ responses indicate a discontinuous transmission (DTX).

What is claimed is: 
     
       1. An operation method of a first terminal in a communication system supporting sidelink communication, the operation method comprising:
 receiving configuration information from a base station including one or more information elements used to declare a radio link failure (RLF); 
 transmitting one or more sidelink data to a second terminal; 
 performing a monitoring operation to receive one or more hybrid automatic repeat request (HARQ) responses for the one or more sidelink data from the second terminal; 
 comparing a number of the one or more HARQ responses, indicating a discontinuous transmission (DTX), received within a predetermined time period and a preset threshold; 
 declaring the RLF for a radio link between the first terminal and the second terminal when the number of the one or more HARQ responses indicating the DTX is greater than or equal to the preset threshold; 
 transmitting, to the base station, information indicating that the RLF is declared; and 
 receiving, from the base station, configuration information of sidelink resources between the first terminal and the second terminal in response to the information indicating that the RLF is declared, 
 wherein the one or more information elements include a DTX-NACK (discontinuous transmission-negative acknowledgement) indicator indicating to transmit a NACK when a DTX situation occurs between the first terminal and the second terminal, and each of the one or more HARQ responses is the NACK, and 
 wherein, when the number of the one or more HARQ responses indicating the DTX is less than the preset threshold, the RLF is not declared. 
 
     
     
       2. The operation method according to  claim 1 , wherein the one or more sidelink data are transmitted to the second terminal through semi-persistent scheduling (SPS) resources, configured grant (CG) resources, or resources scheduled by sidelink control information (SCI). 
     
     
       3. The operation method according to  claim 1 , further comprising transmitting, to the base station, information that the RLF is declared. 
     
     
       4. The operation method according to  claim 1 , further comprising, when the RLF is declared, performing an operation of releasing sidelink resources configured for the radio link in which the RLF is declared. 
     
     
       5. An operation method of a first terminal in a communication system supporting sidelink communication, the operation method comprising:
 receiving configuration information from a base station including one or more information elements used to declare a radio link failure (RLF); 
 transmitting one or more sidelink data to a second terminal; 
 performing a monitoring operation to receive one or more hybrid automatic repeat request (HARQ) responses for the one or more sidelink data from the second terminal; 
 comparing a number of the one or more HARQ responses which are not received within a predetermined time period and a preset threshold; 
 declaring the RLF for a radio link between the first terminal and the second terminal when the number of the one or more HARQ responses which are not received is greater than or equal to the preset threshold; 
 transmitting, to the base station, information indicating that the RLF is declared; and 
 receiving, from the base station, configuration information of sidelink resources between the first terminal and the second terminal in response to the information indicating that the RLF is declared, 
 wherein the one or more information elements include a DTX-NACK (discontinuous transmission-negative acknowledgement) indicator indicating not to transmit a NACK when a DTX situation occurs between the first terminal and the second terminal, and 
 wherein, when the number of the one or more HARQ responses which are not received is less than the preset threshold, the RLF is not declared. 
 
     
     
       6. The operation method according to  claim 5 , wherein the one or more HARQ responses are consecutive HARQ responses. 
     
     
       7. The operation method according to  claim 5 , wherein the configuration information includes the preset threshold that is a comparison criterion of the number of the one or more HARQ responses. 
     
     
       8. The operation method according to  claim 5 , further comprising transmitting, to the base station, information that the RLF is declared. 
     
     
       9. The operation method according to  claim 5 , further comprising, when the RLF is declared, performing an operation of releasing sidelink resources configured for the radio link in which the RLF is declared. 
     
     
       10. An operation method of a base station in a communication system supporting sidelink communication, the operation method comprising:
 transmitting configuration information including one or more information elements used to declare a radio link failure (RLF) for a sidelink to one or more terminals; 
 receiving information indicating that an RLF is declared from a first terminal among the one or more terminals, the RLF being occurred between the first terminal and a second terminal; 
 releasing a sidelink resource configured for a radio link associated with the RLF; 
 reconfiguring a sidelink resource for the sidelink communication between the first terminal and the second terminal; and 
 transmitting configuration information of the reconfigured sidelink resource to the first terminal, 
 wherein the one or more information elements include information indicating a number of RLF-hybrid automatic repeat request (RLF-HARQ) responses, information indicating an RLF period, and a DTX-NACK (discontinuous transmission-negative acknowledgement) indicator, 
 wherein the RLF is declared at the first terminal when the first terminal receives at least one HARQ response indicating a DTX and a number of the at least one HARQ response received within the RLF period is greater than or equal to the number of RLF-HARQ responses, and 
 wherein the DTX-NACK indicator is set to a first value to indicate that a NACK is not transmitted when a DTX situation occurs between the first terminal and the second terminal, and the DTX-NACK indicator is set to a second value to indicate that the NACK is transmitted when the DTX situation occurs between the first terminal and the second terminal. 
 
     
     
       11. The operation method according to  claim 10 , wherein the configuration information includes information indicating a channel busy ratio (RLF-CBR) threshold.